The drug originally tested in hypertensives with low RBC K uptake, independently of cell Na content, dietary intake or drugs, became an effective and predictable method to improve RBC K homeostasis that is critically related to other red-cell functions, such as the pH regulation and oxygen delivery. More important, the observation that reversal of the abnormal RBC K content was associated with a decline and better control of BP, fasting plasma glucose, and regression of ST-T alteration related to LVH or CHD, led us to evaluate the role of RBC in the mechanism of H/K exchange, tissue oxygenation in health and disease states.